A parallel plate capacitor is charged to a potential difference V by a dc source. The capacitor is then disconnected from the source. If the distance between the plates in doubled, state with reason how the following will change,
(i) electric field between the plates,
(ii) capacitance and
(iii) energy stored in the capacitor.

Explanation

To solve the problem step by step, we will analyze how the electric field, capacitance, and energy stored in a parallel plate capacitor change when the distance between the plates is doubled after disconnecting from a DC source.

### Step 1: Electric Field Between the Plates

The electric field (E) between the plates of a parallel plate capacitor is given by the formula:
\[ E = \frac{\sigma}{\epsilon_0} \]
where:
- \( \sigma \) is the surface charge density (charge per unit area),
...